Publications by authors named "A Zechner"

In December 2016 the clinical operation has started at the particle therapy centre MedAustron, Wiener Neustadt, Austria. Different commercial immobilisation devices are used for head patients. These immobilisation devices are a combination of table tops (Qfix BoS™ Headframe, Elekta HeadStep™), pillows (BoS™ Standard pillow, Moldcare®, HeadStep™ pillow) and thermoplastic masks (Klarity Green™, Qfix Fibreplast™, HeadStep™ iCAST double).

View Article and Find Full Text PDF

The ratio of patients who need a treatment adaptation due to anatomical variations at least once during the treatment course is significantly higher in light ion beam therapy (LIBT) than in photon therapy. The ballistic behaviour of ion beams makes them more sensitive to changes. Hence, the delivery of LIBT has always been supported by state of art image guidance.

View Article and Find Full Text PDF

Purpose: Couch-mounted cone-beam computed tomography (CBCT) imaging devices with independently rotatable x-ray source and flat-panel detector arms for acquisitions of arbitrary regions of interest (ROI) have recently been introduced in image-guided radiotherapy (IGRT). This work analyzes mechanical limitations and gravity-induced effects influencing the geometric accuracy of images acquired with arbitrary angular constellations of source and detector in nonisocentric trajectories, which is considered essential for IGRT. In order to compensate for geometric inaccuracies of this modality, a 9-degrees-of-freedom (9-DOF) flexmap correction approach is presented, focusing especially on the separability of the flexmap parameters of the independently movable components of the device.

View Article and Find Full Text PDF

Image guidance during highly conformal radiotherapy requires accurate geometric calibration of the moving components of the imager. Due to limited manufacturing accuracy and gravity-induced flex, an x-ray imager's deviation from the nominal geometrical definition has to be corrected for. For this purpose a ball bearing phantom applicable for nine degrees of freedom (9-DOF) calibration of a novel cone-beam computed tomography (CBCT) scanner was designed and validated.

View Article and Find Full Text PDF

In recent years, depot neuroleptics have gained in importance in the outpatient treatment of chronic schizophrenics. These neuroleptics make drug therapy safer than before, thus improving the prerequisites for socio-therapeutic and rehabilitative measures. The present study analyses the ranking and value of this kind of treatment in the management of outpatients.

View Article and Find Full Text PDF